1. Field of the Invention
This invention pertains to the field of doorbells, ringers and other signaling devices such as are installed near a doorway of a dwelling and used to announce the arrival of visitors.
2. State of the Prior Art
Exterior doors of homes and other dwellings are commonly equipped with a doorbell by which a visitor may announce him or herself to those inside the dwelling. The doorbells typically include a push-button electrical switch mounted on an exterior wall or other support outside the dwelling. The doorbell switch is operatively connected, either by electrical wiring or a wireless link, to an interior signaling device such as an electromechanical ringer or electronic tone generator mounted inside the dwelling. The interior signaling device is actuated when the exterior doorbell switch is pressed by a visitor.
Such doorbells are, however, subject to abuse when repeatedly or continuously pressed by pranksters or others intent on annoying or harassing the occupants of the dwelling, or simply by an impatient visitor who repeatedly or continuously rings the bell until someone responds.
Three forms of abusive doorbell ringing can be identified. A first form of abuse occurs when the door bell is rung repeatedly many times in rapid succession within a relatively short period of time. A second form of abuse occurs when the door bell is rung only a few times but with rings of excessively long duration, such that each ring alone would not be objectionable but in combination the rings add up to excessive bell ringing time within some preset time interval. A third form of abuse occurs where the door bell is rung only once but is rung continuously for an unacceptably long time.
Many modem doorbells are partially protected from abuse in that actuation of the ringer results in playback of a musical tune or sound effect stored in the signaling device, and repeated actuation of the doorbell is ineffective until the tune or sound effect has played out. However, when a short tune or sound effect is selected by the homeowner, the doorbell can be rung repeatedly at an annoyingly high rate. Even long-playing tunes can be replayed unnecessarily. And in continuous ring mode, the doorbells are subject to all forms of abuse mentioned earlier.
Existing doorbell installations lack adequate protection against such abuse and as of yet no practical solution has been proposed to this problem. A continuing need exists for doorbells with built-in protection against harassment caused by abusive ringing of doorbells.